Monitoring potential ionospheric changes caused by the Van earthquake (<i>M</i>_w7.2)

Many scientists from different disciplines have studied earthquakes for many years. As a result of these studies, it has been proposed that some changes take place in the ionosphere layer before, during or after earthquakes, and that the ionosphere should be monitored in earthquake prediction studies. This study investigates the changes in the ionosphere created by the earthquake with a magnitude of Mw=7.2 in the northwest of Lake Erçek, which is located to the north of the province of Van in Turkey on 23 October 2011 and at 13:41 local time (−3 UT) with the epicenter of 38.75∘ N, 43.36∘ E using the TEC values obtained by the global ionosphere models (GIMs) created by IONOLAB-TEC and CODE. In order to see whether the ionospheric changes obtained by the study in question were caused by the earthquake or not, the ionospheric conditions were studied by utilizing indices providing information on solar and geomagnetic activities (F10.7 cm, Kp, Dst). One of the results of the statistical test of the TEC values obtained from both models is positive and negative anomalies obtained for the times before, on the day of and after the earthquake, and the reasons for these anomalies are discussed in detail in the last section of the study. As the ionospheric conditions on the analyzed days were highly variable, it was thought that the anomalies were caused by geomagnetic effects, solar activity and the earthquake.

A Comprehensive Analysis of Ionospheric Anomalies before the Mw7·1 Van Earthquake on 23 October 2011

In this study, possible ionospheric precursors of the Mw7·1 Van earthquake are investigated with temporal, spatial and spectral analyses. For this purpose, Global Navigation Satellite System (GNSS) data of 11 International GNSS Service (IGS) stations and 17 Turkish National Permanent Real-Time Kinematic (RTK) Network (TNPGN-Active) stations were utilised. In addition, Global Ionosphere Map (GIM) data produced by the Center for Orbit Determination in Europe (CODE) was used to obtain GIM-vertical Total Electron Content (vTEC) values for the epicentre. The results of the temporal and spectral analysis indicate an increase (2–8 Total Electron Content Units (TECU)) before the Van earthquake occurred on 9 October, 15–16 October and 21–23 October within 15 days, 8–9 days and 1–3 days prior to the earthquake. The Cross-Wavelet Transform (CWT) method was used to examine the presence of correlation between noticeable variations and space-weather. It is deduced from the CWT analysis that the anomalies should originate from either solar effects or the Van earthquake due to coupling between the F10·7 solar activity index and TEC variations on the anomaly days. The results demonstrate that interdisciplinary approaches and various methods including frequency domain could be used to determine the presence of an earthquake-related anomaly in the ionosphere accurately.

Investigation of the perception about earthquake based on elementary school students’ opinionsDepreme ilişkin algının deprem yaşayan ilköğretim öğrencilerinin görüşlerine dayalı olarak incelenmesi

<p>Earthquakes, which disturb the routine of life, influence psychology of adults and children negatively as the other disasters. In addition to that earthquakes can cause the psychological distress in children such as cognitive, emotional and behavioral problems as well as lack of confidence and despair against future. In order to scope of interventions after earthquake, it can be significant to reveal how the elementary school students experienced and perceived the earthquake after that disaster. For this purpose, the students’ perceptions of the earthquake and psycho-social impacts of that among students have been studied according to the opinions of those. The research is done based on descriptive survey model within the qualitative research model including semi-structured interview method. The subject group of the research is 23 volunteers consisting of 12 girls and 11 boys all of whom experienced the Van earthquake attending secondary school at Van city center. Moving onto the results, students stated that they were outside; they were running their homes to find out the status of their families during the earthquake and just after that.</p><p> </p><p><strong>Özet</strong></p><p>Yaşamın doğal akışını bozan diğer afetler gibi depremler de, hem yetişkinlerin ve hem de çocukların psikolojisi üzerinde birçok olumuz etkiler bırakır. Depremler, çocuklarda birçok bilişsel, duyuşsal ve davranışsal problemin yanı sıra, güven duygusunun yitimi ve geleceğe karşı umutsuzluk gibi psikolojik sorunlara neden olabilir. Deprem yaşayan ilköğretim öğrencilerinin depremi nasıl deneyimlediklerinin ve anlamlandırdıklarının bilinmesi deprem sonrası uygulanabilecek müdahaleler kapsamında önemlidir. Bu amaçla bu araştırmada öğrencilerin depreme ilişkin algıları ve depremin öğrenciler üzerindeki psiko-sosyal etkileri, Van depremini yaşayan ilköğretim öğrencilerinin görüşlerine dayalı olarak belirlenmesine çalışılmıştır. Araştırma, nitel araştırma kapsamında tarama modelinde gerçekleştirilmiş olup yarı yapılandırılmış görüşme tekniği kullanılmıştır. Araştırmanın çalışma grubu, Van İl Merkezinde bulunan ilköğretim okullarının ikinci kademesinde okuyan, Van Depremi’ni yaşayan ve araştırmaya gönüllü katılan 12 kadın; 11 erkek olmak üzere toplam 23 öğrenciden ibarettir. Araştırmada öğrenciler, deprem olduğu sırada ve sonrasında dışarıda olduklarını, kaçtıklarını, eve ailelerinin durumunu öğrenmek için hemen eve geldiklerini belirtmişlerdir.</p>

Time-dependent analysis of aftershock events and structural impacts on intraplate crustal seismicity of the Van earthquake (Mw 7.1, 23 October 2011), E-Anatolia

The Van earthquake (M W 7.1, 23 October 2011) in E-Anatolia is typical representative of intraplate earthquakes. Its thrust focal character and aftershock seismicity pattern indicate the most prominent type of compound earthquakes due to its multifractal dynamic complexity and uneven compressional nature, ever seen all over Turkey. Seismicity pattern of aftershocks appears to be invariably complex in its overall characteristics of aligned clustering events. The population and distribution of the aftershock events clearly exhibit spatial variability, clustering-declustering and intermittency, consistent with multifractal scaling. The sequential growth of events during time scale shows multifractal behavior of seismicity in the focal zone. The results indicate that the extensive heterogeneity and time-dependent strength are considered to generate distinct aftershock events. These factors have structural impacts on intraplate seismicity, suggesting multifractal and unstable nature of the Van event. Multifractal seismicity is controlled by complex evolution of crustal-scale faulting, mechanical heterogeneity and seismic deformation anisotropy. Overall seismicity pattern of aftershocks provides the mechanism for strain softening process to explain the principal thrusting event in the Van earthquake. Strain localization with fault weakening controls the seismic characterization of Van earthquake and contributes to explain the anomalous occurrence of aftershocks and intraplate nature of the Van earthquake.